Continuous Energy Supply Research Articles

Comparative study of performance enhancement of latent thermal energy storage system with copper porous fin

Phase change material (PCM)-based thermal energy storage (TES) has attained significant attraction towards energy savings and ensures a continuous energy supply. However, the lower thermal conductivity of PCM impedes the efficient transfer in the storage systems, thereby causing longer charging time. Therefore, this paper introduces a novel heat transfer augmentation technique by incorporating copper porous fins in the shell-tube latent heat thermal energy storage. Further, to demonstrate the contribution of porous fins in heat transfer improvement, full-foam, solid-fin and without-fin TES systems are also evaluated and compared. A two-dimensional axisymmetric numerical model is developed and validated with in-house experimental results. It is found that conduction strongly affects the solidification process, exhibiting a greater response rate than the melting process of heat transfer enhancement techniques. Full-foam has higher melting and solidification rates, followed by solid-fin, porous-fin and without-fin. Compared to the without-fin configuration, the temperature response rates of the full-foam, solid-fin and porous-fin are improved by 169.9 %, 44.8 % and 41.88 %, respectively, during the melting process. Moreover, it is revealed that the porosity of foam has a marginally higher impact on the liquid fraction than the pore density. Further, the inclusion of porous-fin and full-foam leads to more uniform temperature distribution in PCM during melting and solidification compared to solid fin and without-fin. Therefore, the porous-fin and full-foam may be utilised for electronic cooling and battery thermal management, which requires uniform cooling at faster rates.

On the study of a thermal system for continuous cold energy harvesting and supply from LNG regasification

On the study of a thermal system for continuous cold energy harvesting and supply from LNG regasification

Evaluating the environmental impact and economic practicability of solar home lighting systems: a roadmap towards clean energy for ecological sustainability.

The vitality contribution is a vital cause for defensible monetary improvement and collective success by eradicating poverty. Adopting the solar home lighting system (SHLS) is advantageous not only in social lifestyles but also improves the health of family members and increases home-based small businesses activities due to the inexpensive and continuous supply of energy. The main aims of the study are to scrutinize the most substantial barriers to adopting SHLS in Pakistan. A comprehensive, structured questionnaire appraisal was conducted for sample size with the help of non-probability sampling (purposive sampling), and primary data was collected. The designated hypotheses were evaluated using partial least square structural equation modeling (PLS-SEM). In the present study, we validate the model using a sample of 271 adopters of SHLS contributed as respondents. The results disclose that entire autonomous variables expressively and positively correlated with adopting SHLS dipping energy disasters and improving home-based small business activities. Correspondingly, social media-based awareness of SHLS significantly moderates and positively affects the selected factors in this study. Empirical results indicate that prudently eradicating maintenance barriers with experienced professionals, subsidy in prices from the government, quality base satisfaction of owners, and social media-based awareness are the primary tools to adopt SHLS. Additionally, the outcomes offer valuable suggestions to the competent authorities that introduce encouragement and maintenance policy for adopting SHLS.

Current density and thermal propagation of electromagnetic CoFe2O4 and TiO2/C2H6O2 + H2O hybridized Casson nanofluids: A concentrated solar power maximization

The limited availability of fossil fuel, ecosystem consideration and economic factor stimulates interest in alternative energy provision and thermal energy enhancement. Utilization of solar radiation and nanofluids with solid tiny particle provides a platform to optimize renewable solar thermal system performance. Owing to its usages, this study examines thermal transfer and current density of electromagnetic gravity driven Casson hybridized nanofluid flow through partially filled porous media with Ohmic heating. A mixture of cobalt ferrite (CoFe2O4) and titanium dioxide (TiO2) is considered for the nanoparticles thermal propagation in base solvent ethylene-glycol+water (C2H6O2+H2O). A parabolic concentrated solar collector is used for the solar radiation absorption with a continuous energy supply. An invariant transformation of the partial derivative model is obtained using similarity variables. A semi-analytical shifted Chebyshev method coupled with the integrated collocation scheme has been adopted to provide theoretical solutions to the model. The study revealed that concentrated solar power current density is raised as the electric field factor and medium porosity is increased. The fluid velocity is damped while the temperature distribution is enhanced as the nanoparticle volume fraction is boosted. Thus, this investigation will improve the efficiency of thermal engineering products and enhance industrial performance.

A Hybrid Triboelectric-Electromagnetic Nanogenerator Based on Arm Swing Energy Harvesting

As wearable devices continue to be updated and iterated, there is an increasing demand for energy supplies that are small, portable and capable of working continuously for extended periods of time. Here, a hybrid triboelectric-electromagnetic nanogenerator (HNG) based on a biomechanical energy harvester is demonstrated. The HNG is designed to be worn on the wrist according to the curve of the wearer’s arm swing. During the swinging of the arm, the magnet covered by the PTFE film will move relative to the curved cavity of the HNG and take on a negative charge by rubbing against the inner wall of the Cu coated cavity, resulting in a change in the potential difference between the two copper electrodes on the inner wall of the curved cavity. The movement of the magnet causes the magnetic flux of the three pairs of coils on both sides of the arc track to change to produce the induced electric potential, which converts the mechanical energy generated by the arm swing into electrical energy. After the rational design, the HNG is integrated into a small size device to achieve the collection of biomechanical energy. Several experiments were conducted to verify the HNG’s usability. Experiments show that the HNG takes 90 s to charge from 0 V to 1.2 V for a 1000 μF capacitor. In addition, the HNG can light up 23 LEDs simultaneously and provide a continuous supply of energy to portable electronic devices, such as temperature sensors and electronic watches after the capacitor has stored the energy. Furthermore, the HNG is experimentally verified by volunteers wearing the HNG to achieve continuous and stable output in all three states of slow swing, fast swing and running swing. This work not only provides a useful reference for human biomechanical energy harvesting, but can also provide a continuous, clean source of energy for wearable devices.

High-Throughput Image-Based Quantification of Mitochondrial DNA Synthesis and Distribution.

The vast majority of cellular processes require a continuous supply of energy, the most common carrier of which is the ATP molecule. Eukaryotic cells produce most of their ATP in the mitochondria by oxidative phosphorylation. Mitochondria are unique organelles because they have their own genome that is replicated and passed on to the next generation of cells. In contrast to the nuclear genome, there are multiple copies of the mitochondrial genome in the cell. The detailed study of the mechanisms responsible for the replication, repair, and maintenance of the mitochondrial genome is essential for understanding the proper functioning of mitochondria and whole cells under both normal and disease conditions. Here, a method that allows the high-throughput quantification of the synthesis and distribution of mitochondrial DNA (mtDNA) in human cells cultured in vitro is presented. This approach is based on the immunofluorescence detection of actively synthesized DNA molecules labeled by 5-bromo-2'-deoxyuridine (BrdU) incorporation and the concurrent detection of all the mtDNA molecules with anti-DNA antibodies. Additionally, the mitochondria are visualized with specific dyes or antibodies. The culturing of cells in a multi-well format and the utilization of an automated fluorescence microscope make it easier to study the dynamics of mtDNA and the morphology of mitochondria under a variety of experimental conditions in a relatively short time.

Analisa Dan Rancang Bangun Alat Pendeteksi Gangguan Fuse Cut Out Melalui Notifikasi Telegram Berbasis Global Positioning System

The electric power system must be able to provide a continuous supply of electrical energy with a standard amount of voltage and frequency in accordance with applicable regulations and the system must immediately return to normal conditions if the system experiences a disturbance. This tool is used to detect faults and the location of the fuse cut out (FCO). PZEM-004T sensor to read the voltage of each phase. Neo-6M GPS to get the coordinates of the location which is accessed via Google Map, then the Telegram bot sends a message to the feeder status information, the location connected to the Google Map, the transformer address and the voltage value after the disturbance. The average difference between the actual location distance to the location recorded by GPS NEO-6M is 4.10 meters and recorded by GPS Coordinates is 6.90 meters. The average percentage error of voltage values for each phase in the measuring instrument and in the sensor is in the R = 0.62 % phase, S = 8.94 % and T = 8.57 %. The Telegram bot sends a message when the FCO in the S phase is decided, namely the S Phase status is Lost, because the voltage in the S phase decreases from 221.9 V AC to 117.7 V AC, with the average duration of sending Telegram bot messages is 41.3 seconds.

Impact of Tourist Areas on the Electrical Grid: A Case Study of the Southern Dominican Republic

The growing integration of tourist areas and complexes increases the demand for electrical power systems. This increased demand may represent a vulnerability to voltage and frequency stability in electrical grids, where these parameters are essential for an optimal and continuous supply of electrical energy. The Dominican Republic has begun a tourist expansion process in areas that were previously not commercially exploited. Based on the factors mentioned above, this article’s objective was to analyze the impact caused by the increase in electricity demand due to the tourism sector, using the Enriquillo Region of the Dominican Republic as a case study. The impacts of this expansion on the voltage profiles and the system’s frequency were determined. The methodology consisted of obtaining information on the mathematical model of the system to evaluate the expansion plan for the study period and the projection of the demand of the grid. The complete system was modeled with this information, including expansion and possible renewable generators. Finally, the flow of charges was measured, and dynamic analysis was carried out. The quasi-dynamic and RMS/EMT simulations were carried out in the DIgSILENT software for this investigation. The results showed that the electrical system benefits stability and national standards. This is because the transmission lines reduced their loading by approximately 2.99% in 2032. As the years of study passed and the system load increased, the voltage in the bars of the 138 kV systems and generators did not exceed the range of ±5% established in the technical regulations of the Dominican electricity market.

Self-excited asynchronous generator with PV array in detained autonomous generation systems

<span lang="EN-US">It's important to examine and handle the issue of green energy generation in inaccessible locations. Nonrenewable hybrid power has environmental and economic impacts. Reliable electricity and energy efficiency are priorities. Renewable energy that is eco-friendly and doesn't affect the environment. Solar and wind power, two ecologically benign and load-sharing-capable forms of renewable energy, are included in this technique. At the same time, solar power will keep the load voltage balanced and the system stable thanks to the inclusion of a DC-DC converter. The asynchronous generator has been selected because of its low maintenance needs and extended service life; nevertheless, the voltage on the load side is unbalanced when this machine is in operation. An asynchronous generator can be a viable alternative to well-developed synchronous generators for use in wind turbines or small hydro generators because they have relatively inexpensive costs, are simple, require inadequate maintenance, possess adequate resistance to wear and tear, and have reduced overload damage. It is difficult to maintain a continuous supply of energy in faraway regions because of the lack of related work in the power distribution networks. This problem is addressed in this paper by a well-designed converter that maintains a constant output voltage.</span>

A green, secure, and deep intelligent method for dynamic IoT-edge-cloud offloading scenarios

To fulfill people's expectations for smart and user-friendly Internet of Things (IoT) applications, the quantity of processing is fast expanding, and task latency constraints are becoming extremely rigorous. On the other hand, the limited battery capacity of IoT objects severely affects the user experience. Energy Harvesting (EH) technology enables green energy to offer a continuous energy supply for IoT objects. It provides a solid assurance for the proper functioning of resource-constrained IoT objects when combined with the maturation of edge platforms and the development of parallel computing. The Markov Decision Process (MDP) and Deep Learning (DL) are used in this work to solve dynamic online/offline IoT-edge offloading scenarios. The suggested system may be used in both offline and online contexts and meets the user's quality of service expectations. Also, we investigate a blockchain scenario in which edge and cloud could work toward task offloading to address the tradeoff between limited processing power and high latency while ensuring data integrity during the offloading process. We provide a double Q-learning solution to the MDP issue that maximizes the acceptable offline offloading methods. During exploration, Transfer Learning (TL) is employed to quicken convergence by reducing pointless exploration. Although the recently promoted Deep Q-Network (DQN) may address this space complexity issue by replacing the huge Q-table in standard Q-learning with a Deep Neural Network (DNN), its learning speed may still be insufficient for IoT apps. In light of this, our work introduces a novel learning algorithm known as deep Post-Decision State (PDS)-learning, which combines the PDS-learning approach with the classic DQN. The system component in the proposed system can be dynamically chosen and modified to decrease object energy usage and delay. On average, the proposed technique outperforms multiple benchmarks in terms of delay by 4.5%, job failure rate by 5.7%, cost by 4.6%, computational overhead by 6.1%, and energy consumption by 3.9%.

Hierarchical multi-agent reinforcement learning for repair crews dispatch control towards multi-energy microgrid resilience

Extreme events are greatly impacting the normal operations of microgrids, which can lead to severe outages and affect the continuous supply of energy to customers, incurring substantial restoration costs. Repair crews (RCs) are regarded as crucial resources to provide system resilience owing to their mobility and flexibility characteristics in handling both transportation and energy systems. Nevertheless, effectively coordinating the dispatch of RCs towards system resilience is a complex decision-making problem, especially in the context of a multi-energy microgrid (MEMG) with enormous dynamics and uncertainties. To this end, this paper formulates the dispatch problem of RCs in a coupled transportation and power-gas network as a decentralized partially observable Markov decision process (Dec-POMDP). To solve this Dec-POMDP, a hierarchical multi-agent reinforcement learning (MARL) algorithm is proposed by featuring a two-level framework, where the high-level action is used for switching decision-making between transportation and power-gas networks, and the lower-level action constructed via the multi-agent proximal policy optimization (MAPPO) algorithm is used to compute the routing and repairing decisions of RCs in the transportation and power-gas networks, respectively. The proposed algorithm also introduces an abstracted critic network by integrating the load restoration status, which captures the system dynamics and stabilizes the training performance with privacy protection. Extensive case studies are evaluated on a coupled 6-bus power and 6-bus gas network integrated with a 9-node 12-edge transportation network. The proposed algorithm outperforms the conventional MARL algorithms in terms of policy quality, learning stability, and computational performance. Furthermore, the dispatch strategies of RCs are analyzed and their corresponding benefits for load restoration are also evaluated. Finally, the scalability of the proposed method is also investigated for a larger 33-bus power and 15-bus gas network integrated with an 18-node 27-edge transportation network.

Energy Management of an Autonomous Photovoltaic System under Climatic Variations

Predictable and unpredictable variations are two major causes of renewable energy-related intermittency. Such a drawback could be overcome by applying new energy management strategies, particularly storage systems. This paper investigates the feasibility of introducing a photovoltaic management string, enabling the maintenance of continuous energy supply storage capacity. Accordingly, the PV system is liable to perform at maximum efficiency following the implementation of an MPPT-controlled DC/DC boost converter of the Perturb and Observe (P&O) type. Most of the energy-management approaches target goals lie mainly in optimizing the energy resources’ operational and storage capacities. The current MATLAB/Simulink-based simulation study achieved results that turned out to testify well to the advanced design’s high performance and efficiency in maintaining the load’s energy autonomy while increasing the battery’s life span.

Effects of meteorological and climatological factors on extremely high residual load and possible future changes

Under high variable renewable energy (VRE) penetration, the occurrence of low VRE production, such as dark doldrums (Dunkelflaute) and wind-solar drought, can threaten a secure and continuous energy supply owing to an imbalance between electricity demand and supply. In this study, historically reconstructed long-term VRE generation and electricity demand were used to investigate the relationship between extremely high residual load (demand minus VRE output) and weather/climate in Japan. The impact of changes in the VRE's installed capacity on this relationship was also investigated using three simple future target scenarios. The results showed that the increase in installed VRE capacity causes greater daily and weekly residual load variabilities and affects the seasonality of its peaks. To study the weather patterns associated with high residual load events, self-organizing maps were applied to atmospheric circulation fields derived from atmospheric reanalysis data. The high residual load was associated with enhanced cold surge-type weather patterns during winter at the current low VRE installation level. However, under future increased VRE penetration, the weather patterns leading to high residual load will change to cloudy-windless types typically caused by a southern coastal extratropical cyclone. There is also considerable interannual variability in the frequency of high residual load events, which changed significantly with increasing VRE capacity. It is crucial to incorporate the dependence of climatic conditions into designing power systems to maintain the stability of a power system under future conditions.

Increasing in efficiency of surface hardening of structural steels by HFC hardening and ultrasonic treatment

The surface plastic deformation of structural steels was studied using ultrasound. Four variants of hardening are considered: ultrasonic treatment with continuous supply of ultrasonic energy, pulsed ultrasonic treatment, a combination of ultrasonic treatment followed by pulsed treatment, and ultrasonic treatment after quenching with induction heating. It is shown that UST increases the microhardness of the surface layer of structural steels by 1.5 times, HFC hardening by more than 2 times, combinations of HFC hardening + UST by 3 times, and HFC + UST hardening by 3.2 times. Ultrasonic treatment increases the compressive stresses that occur in the steel surface hardened by HFC hardening. Compressive stresses increase especially strongly after pulsed ultrasonic treatment with five passes and reach a value of 1200 MPa.

Effective combined surface hardening processes of structural steels using ultrasound

The effectiveness of hardening of the surface layer of machine parts is evaluated by the operational properties of the surface layer and depends on many conditions that characterize the specific features of the technological process in which this method of hardening is carried out. The surface plastic deformation of structural steels with the use of ultrasound is studied. Four variants of hardening are considered: ultrasonic treatment with continuous supply of ultrasonic energy, pulse ultrasonic treatment, combination of ultrasonic treatment with subsequent pulse treatment, ultrasonic treatment after hardening with induction heating. It is shown that ultrasonic treatment increases microhardness of surface layer of structural steels by 1.5 times, HF hardening by more than 2 times, HF hardening + UZO combination by 3 times and HF hardening + IUZO combination by 3.2 times. Ultrasonic treatment increases compression stresses occurring in steel surface hardened by HFI hardening. The compressive stresses increase especially strongly after pulse ultrasonic treatment with five passes and reach the value of 1200 Pa.

Autonomous heat-cooling and power supply system based on renewable energy devices (trigeneration system)

The article presents the results of research on the possibilities of providing heat-cooling and electricity supply systems to autonomous consumers located far from centralized energy supply in the southern regions of Uzbekistan (Bukhara and Kashkadarya) based on renewable energy sources. In these regions, the average daily relative solar energy is 4.5 kWh/m2/day, the average wind speed is 5.5...8.5 m/s, the relative energy is 300...580 W/m2, and the underground low-potential temperature at a depth of 3...5 m, on average, is +10...+12oC. Analyzes of scientific research conducted on the development and reliability of trigeneration systems in the world are presented, and the possibilities of using these systems in our region are based. A combined solar-wind power plant, which is adapted to the climatic conditions of the southern regions of Uzbekistan, works efficiently in weak wind currents and high temperature regimes, and a complex energy system consisting of geothermal heat pumps that produce continuous heat and cold energy in different temperature regimes is offered. The proposed complex power plant allows for continuous and reliable energy supply to autonomous consumers located far from the centralized energy supply.

Numerical analysis on lunar heat storage system: Multi-objective optimization, heat storage capacity, and thermal insulation performance

The long lunar night of 14 earth days without solar radiation has become the biggest obstacle to the continuous energy supply system day and night. The lunar base heat storage system is one of the best solutions because it is possible to transfer energy from day to night for power generation. However, due to the diversity of energy demands of the lunar base, it is inevitable to study the thermal storage performance of the heat storage system at different periods. In this paper, based on three objective parameters: effective time of heat storage (teff), heat storage capacity (Q), and system entropy increase (Sgen) of the heat storage process, a multi-objective optimization design of heat storage system is carried out. In addition, to solve the heat dissipation problem of the lunar night, the natural lunar regolith insulation layer was added to evaluate the heat storage and insulation of the lunar night. The results show that different types of the heat storage system can be obtained by changing the structure parameters. The heat storage efficiency of the heat storage system with a large radius is still 0.59 after a long period of heat storage. The minimum thickness of the varied-temperature layer can be reduced to 60 % of the height of the whole system. Additionally, the insulation layer can effectively reduce energy loss at night, but the effect of improving thermal insulation performance is limited when the insulation layer thickness is too thick.

Recent Advancements in Evacuated Tube Solar Water Heaters: A Critical Review of the Integration of Phase Change Materials and Nanofluids with ETCs

Evacuated tube solar water heaters are gaining more attention in the present market scenario as compared to conventional collectors. Such collectors are versatile because no solar tracking is required and the operating temperature range is also broad. Comparatively, it is cost-effective and may attain higher thermal efficiency. However, like other collectors, continuous energy supply is sometimes hampered by the intermittent nature of solar radiation. This problem can be partially resolved by using phase change materials (PCM) in the evacuated tube solar collector (ETC). PCMs can store the energy during the sunshine hours, which can be released when solar energy is not available. In the literature, several studies are available pertaining to the use of PCMs in ETC-based solar water heaters. The literature indicates that the integration of PCMs with ETCs has several merits. Nevertheless, systematic, and comprehensive review papers dedicated to such integrated energy storage systems with ETC solar water heaters are not available. Hence, the objective of this work is to compile the relevant experimental, numerical, and theoretical works reported in the literature. The present paper broadly reviews the recent design modifications, PCM integration with different kinds of ETC water heaters, and their life cycle assessment. Furthermore, studies in the literature pertaining to the application of nanoparticles in ETC systems are also discussed, and finally, a roadmap for this energy storage system is provided.

Dissecting Flux Balances to Measure Energetic Costs in Cell Biology: Techniques and Challenges

Life is a nonequilibrium phenomenon: Metabolism provides a continuous supply of energy that drives nearly all cellular processes. However, very little is known about how much energy different cellular processes use, i.e., their energetic costs. The most direct experimental measurements of these costs involve modulating the activity of cellular processes and determining the resulting changes in energetic fluxes. In this review, we present a flux balance framework to aid in the design and interpretation of such experiments and discuss the challenges associated with measuring the relevant metabolic fluxes. We then describe selected techniques that enable measurement of these fluxes. Finally, we review prior experimental and theoretical work that has employed techniques from biochemistry and nonequilibrium physics to determine the energetic costs of cellular processes.

Performance analysis of a dish solar thermal power system with lunar regolith heat storage for continuous energy supply of lunar base

Sustainable energy supply is a major challenge for the lunar base because of the lengthy night of the Moon. In-situ resource utilization based on lunar regolith heat storage is a promising solution to this challenge. Herein, a dish solar thermal power system with lunar regolith heat storage is proposed to supply energy to a lunar base. A theoretical model is established using finite-time thermodynamics to investigate system performance in a lunar circadian cycle. A case study shows that the output power and efficiency of the system gradually decrease whether in lunar day or lunar night. The average output power during the lunar day and night is 10.8 kW and 7.0 kW, respectively. The system can achieve a high energy efficiency of 48.0%, which is mainly owing to the full utilization of lunar resources. In addition, the effects of several key parameters on the system performance are discussed and the results show that the energy supply of the system requires a tradeoff between lunar day and night. This work reveals that the proposed system has the potential to supply energy to the lunar base continuously and efficiently, providing a scheme for the energy supply system of the future lunar base.